The invention relates to track guiding guard members used with crawler track vehicles, particularly in rough terrain, such as encountered in road building and logging in mountainous and forested areas.
Crawler track vehicles have a pair of spaced apart endless loops of links, the links being pinned together by link pins for relative articulation between adjacent links. Relatively large area track pads are secured to each link to distribute load of the vehicle onto the ground. It is well known that relative twisting or rotation about a longitudinal axis can occur between lower runs of the crawler track and idlers engaging such runs for transferring weight of the vehicle to the runs. Particularly on rough terrain when the vehicle is traversing rocks, tree stumps, etc., complete weight of the vehicle can sometimes be supported on only three or four track pads of the tracks. If the pads bear the weight off-centre, high asymmetrical loads are applied to the pads which can twist sufficiently to shear the pins connecting the associated links together, and/or the pads themselves can fracture. If the lower run of the track is under relatively low tension, with severe twisting, the lower run can disengage from the idlers, and then from the drive sprocket, that is, the vehicle can "throw a track". It is also well known that crawler track vehicles are prone to damage from material becoming jammed between the track engaging idlers and upper faces of lower runs of the crawler tracks. This can become a problem when the vehicle is operating in relatively deep loose rocks or other loose material The problems identified above have been solved in the main by some prior art guiding guards, but the guards themselves present problems for servicing.
Guiding guard members have been developed which enclose a lower run of the track to support the lower run against twisting and to reduce chances of material falling onto lower runs of the crawler track. One type of guiding guard member or track roller guard is shown in U.S. Pat. No. 2,049,693 issued to the Caterpillar Tractor Co. and used extensively in North America. While the guard serves the intended purpose, it has some disadvantages which can increase cost of operation of the vehicle. For example, the guard is secured to the vehicle by a plurality of vertically disposed nuts and bolts which connect a longitudinal horizontal flange of the guard to a complementary flange of the vehicle. Each guard comprises an essentially continuous heavy vertical plate extending along each side of each crawler track, each plate having a reinforced cut-away portion to provide access for greasing bearings of the idlers. Thus, if the idlers or bearings thereof require maintenance other than routine grease application, usually the guiding guard member must first be removed, which involves removing the plurality of vertically disposed nuts and bolts. Due to the severe operating conditions of many crawler track vehicles, the removal of such nuts and bolts can be highly time consuming and thus routine maintenance of idlers can be costly.
Early examples of the guiding guard members were prone to deflection when subjected to severe interference from the tracks due to terrain obstructions, and thus guards on opposite sides of the track are commonly secured together with transversely disposed bolts which interconnected portions of the guards on opposite sides of each track. Such bolts were also subjected to abuse during use, and increase the time and cost for removal of the track guards.
Commonly, lower portions of the guiding guard members are closely spaced from pins securing links of the lower crawler track run. The small clearance assists in maintaining accurate tracking of the lower run, as well as reducing tendency of material to fall onto the lower run of the track. Examples of the crawler track vehicles with relatively close fitting guiding guard members are shown in U.S. Pat. Nos. 4,006,940 issued to General Motors Corporation of Detroit, Mich. and 4,265,494 issued to Kubota, Ltd. of Japan.
To the inventor's knowledge there are no guiding guard members which permit easy access for servicing bearings of idlers, and permit easy installation and removal of the guards while concurrently being adequately strong to resist lateral deflection when interference occurs between the crawler track and the guiding guard.